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  • 1990-1994  (18)
  • 1955-1959  (2)
  • 1950-1954
  • 1905-1909
  • Polymer and Materials Science  (20)
  • 1
    Electronic Resource
    Electronic Resource
    Transitional properties of liquid-crystalline side-chain polymers derived from poly(p-hydroxystyrene) (1991)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 192 (1991), S. 1495-1508 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A series of liquid-crystalline polystyrene derivatives with ω-(4-(4-fluorophenylazo)phenoxy)-alkoxy pendant groups have been synthesized and characterized. Homologues with four or more methylene units in the spacer chain exhibit smectic liquid-crystalline phases, while the homologue with three methylene units forms an amorphous glass. The smectic A-isotropic (SA-I) transition temperatures show a marked odd-even effect as a function of the parity of the spacer chain. This odd-even behaviour is also found in the variation of ΔS/R at the SA-I transition across the series. A marked hysteresis between the transition temperatures determined on heating and the transition temperatures determined on cooling is observed. A molecular interpretation of these phenomena is proposed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1991.021920704
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  • 2
    Electronic Resource
    Electronic Resource
    Miscibility behavior in blends of poly(2,6-dimethylphenylene oxide) and random or block copolymers of styrene with methyl methacrylate (1990)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 191 (1990), S. 243-250 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The Miscibility in blends of poly(2,6-dimethylphenylene oxide)Systematic IUPAC name: poly[oxy(2,6-dimethyl-1,4-phenylene)]. (PPO) with random or block copolymers of styrene and methyl methacrylate (MMA) was studied by light microscopy and glass transition temperature measurements. Blends of PPO and the random copolymers were found to be miscible up to a copolymer content of 18 wt.-% MMA. The transition from miscibility to immiscibility in these blends in independent of temperature in the range 100 to 350°C. From these data, the segmental interaction parameter between units of the homopolymer and MMA, χPPO/PMMA is estimated to be about 0,5. Blends of PPO and the block copolymers of styrene and MMA used behave essentially as the corresponding homopolymers in terms of miscibility.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1990.021910120
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Miscibility in blends of random copolymers of styrene and acrylontrile with block copolymers of styrene and methyl methacrylate (1990)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 191 (1990), S. 1623-1631 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Phase behavior in blends of random copolymers of styrene and acrylonitrile with block copolymers of styrene and methyl methacrylate was studied by light scattering, light microscopy and glass transition temperature measurements. The results are compared with those of respective blends containing random copolymers of styrene and methyl methacrylate. In terms of macrophase separation, the block copolymers display a more extended miscibility domain with styrene/acrylonitrile copolymers than the random copolymers. However, the extent of the miscibility domain varies as a function of temperature. Unlike the random copolymer blends, all blends containing block copolymers exhibit lower critical solution temperature behavior. Finally, it is established that the systems studied here undergo spinodal decomposition leading to macrophase separation.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1990.021910714
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  • 4
    Electronic Resource
    Electronic Resource
    Fourier transform infrared spectroscopy of the polymorphic forms of syndiotactic polystyrene (1990)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 191 (1990), S. 2111-2119 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Infrared spectra of syndiotactic polystyrene exhibiting various crystalline forms and modifications, and in the amorphous state, are reported in this contribution. In addition to strong conformational effects, the spectra demonstrate striking effects of chain packing. Several infrared spectral differences also exist between the two crystalline forms which present a trans-planer conformation of the chains. Spectral changes are also reported for solution-crystallized samples, which depend on the solvent present in the clathrate compound formed with the polymers.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1990.021910914
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  • 5
    Electronic Resource
    Electronic Resource
    The effect of radical trapping reagents upon formation of poly(α-tetrahydrothiophenio para-xylylene) polyelectrolytes by the wessling soluble precursor method (1992)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 30 (1992), S. 2223-2231 
    Details
    ISSN: 0887-624X
    Keywords: poly(arylene vinylene) ; poly(1,4-phenylene vinylene) ; poly(para-phenylene vinylene) ; para-xylylene ; 1,4-benzoquinodimethane ; radical polymerization ; conducting polymers ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Molecular weights were studied by gel permeation chromatography of derivatized poly(α-tetrahydrothiophenio para-xylylene) chloride produced by aqueous or methanolic base-induced polymerization of 1,4-bis(tetrahydrothiopheniomethyl) benzene dichloride, both with and without a variety of added polymerization inhibiting agents. Efficient radical scavenging agents such as 2,2,6,6-tetramethylpiperidinoxyl and hydrogen atom donor 2,4,6-tri-tert-butylaniline reduced the degree of polymerization of the reactive α-(tetrahydrothiophenium chloride)-para-xylylene intermediate produced in this chemistry, and in some cases completely suppressed formation of high polymer. These two traps did not affect the equilibrium production of the para-xylylene by UV-Vis spectral analysis; hence they must affect the subsequent polymerization chain propagation steps in the mechanism. Electron spin resonance studies of polymerization in the presence of 0.00025 equiv of TEMPO showed disappearance of the spin label, a result consistent with a radical scavenging process. The results suggest that production of high molecular weight poly(α-tetrahydrothiophenio para-xylylene) chloride proceeds through a radical chain propagation sequence. © 1992 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1992.080301018
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  • 6
    Electronic Resource
    Electronic Resource
    Para-Xylylenes and analogues by base-induced elimination from 1,4-bis-(dialkylsulfoniomethyl)arene salts in poly(1,4-arylene vinylene) synthesis by the wessling soluble precursor method (1992)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 30 (1992), S. 2233-2240 
    Details
    ISSN: 0887-624X
    Keywords: para-xylylenes ; 1,4-benzoquinodimethanes ; conducting polymers ; poly(arylene vinylene)s ; poly(phenylene vinylene)s ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: para-Xylylenes are generated by treatment of various 1,4-bis(dialkylsulfoniomethyl)arene dihalides with base in water, methanol, and aqueous acetonitrile, as shown by UV-Vis spectroscopy. This procedure allows the monitoring of the transient xylylene monomers that yield polyelectrolyte precursor polymers for poly(arylene vinylene)s, formed by variations of the chemistry developed originally by Wessling and co-workers. Alkoxy, alkyl, and halogen ring substituents on the sulfonium salt precursors do not greatly affect the ability to generate and observe the growth and decay of steady-state concentrations of the para-xylylene intermediates. Use of strong resonance-acceptor substituents - such as cyano or nitro - on the ring reduces production of a strong para-xylylene absorption, possibly due to reluctance of the ylides initially formed from the bis-sulfonium salts to eliminate to the xylylenes. By variation of UV-Vis conditions, it was found that use of 20% aqueous acetonitrile rather than water allowed formation of low to modest molecular weight polyelectrolytes in cyano-substituted cases (Mw = 8000-37,000). Use of UV-Vis test experiments should be useful for screening of bis sulfonium salt precursors that may be expected to give high molecular weight polyelectrolytes - in cases where para-xylylene formation is easy - as well as for finding reaction conditions that will optimize polymer formation. © 1992 John Wiley & Sons, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1992.080301019
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  • 7
    Electronic Resource
    Electronic Resource
    Syntheses of new poly (arylene vinylene) analogues: Poly (4,7-benzofuran vinylene) and poly (4,7-benzothiophene vinylene) (1994)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 32 (1994), S. 65-71 
    Details
    ISSN: 0887-624X
    Keywords: poly(arylene vinylene)s ; conducting polymers ; soluble precursor polymers ; polyelectrolytes ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of bis(4,7-tetrahydrothiopheniomethyl) benzofuran dibromide with aqueous tetramethylammonium hydroxide leads to a water-soluble polyelectrolyte which can be film cast and thermolytically eliminated to give poly(4,7-benzofuran vinylene) (PBFV). Subjection of bis(4,7-tetrahydrothiopheniomethyl) benzothiophene dibromide to the same reaction sequence gives poly(4,7-benzothiophene vinylene) (PBTV). UV-VIS studies show that PBFV has a band gap of 2.76 eV, while PBTV has a band gap of 2.92 eV. These polymers are members of a new class of conjugated poly (arylene vinylene)s, in which heterocyclic pseudoaromatic rings are fused onto a poly(1,4-phenylene vinylene) backbone. © 1994 John Wiley & Sons, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1994.080320108
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  • 8
    Electronic Resource
    Electronic Resource
    Solid-state 13C NMR characterization of annealed poly (p-phenylene vinylene) PPV Films (1990)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 28 (1990), S. 1859-1869 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Solid-state 13C cross-polarization magic-angle spinning (CPMAS) nuclear magnetic resonance (NMR) spectra have been obtained for annealed films of poly (p-phenylene vinylene) (PPV), prepared through the precursor route and for a deuterated PPV-d4, poly (p-2,3,5,6 tetradeuterophenylene vinylene). 13C CPMAS spectra of PPV are of high resolution, typically characteristic of a nearly fully crystalline structure. All four phenylene and vinylene resonances have been assigned, and for stretched films the 13C CPMAS linewidth and the quality of crystallinity are independent of the draw ratio. 13C CPMAS resolution and crystallite size (as determined by transmission electron microscopy, TEM) depend upon final annealing temperature. The greatest NMR resolution and largest crystallite size are obtained for films annealed at 300°C. The 13C CPMAS NMR spectra show the presence of phenylene ring 180° rotational jumps, and 13C CPMAS resolution is affected by rotational disorder about phenylene-vinylene bonds. NMR data show that PPV films possess molecular motion at elevated temperatures. Enhancement of this motion during annealing may provide a means for improving the quality of PPV crystallinity.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1990.090281015
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  • 9
    Electronic Resource
    Electronic Resource
    Thermal, dielectric, and mechanical relaxation in poly(benzimidazole)/poly(etherimide) blends (1991)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 29 (1991), S. 649-657 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Thermal, dielectric, and mechanical relaxation measurements on miscible blends of polybenzimidazole (PBI) and a polyetherimide (PEI, Ultem 1000) prepared by solution casting from dimethylacetamide (DMAc) reveal a number of structurally related features. Annealing below the glass transition temperature induces an enthalpy relaxation process typical of single-phase glasses of nonequilibrium structure. Dielectric relaxation experiments on samples annealed at ambient conditions reveal two relaxation processes below 400°C. At lower temperatures (50-200°C), the desorption of water is observed. Above 200°C in the first run, a composition-dependent relaxation is seen at the highest frequencies (100 kHz) while a relaxation approximately independent of composition appears in the second run. The latter corresponds to the glass transition of the PEI phase. The glass transition of PBI at this frequency is above the degradation temperature. At lower frequencies a strongly dispersive electrode polarization process masks the high-temperature relaxations. Dynamic mechanical results show similar features with respect to phase separation; the main difference is that the tan δ curves in the first run are complicated by the desorption of residual solvent.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1991.090290602
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  • 10
    Electronic Resource
    Electronic Resource
    2H NMR characterization of phenylene ring flip motion in poly(p-phenylene vinylene) films (1992)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 30 (1992), S. 11-18 
    Details
    ISSN: 0887-6266
    Keywords: poly(p-phenylene vinylene), NMR study of phenylene ring motion in ; nuclear magnetic resonance (NMR) of phenylene ring motion in poly(p-phenylene vinylene) ; molecular motion in poly(p-phenylene vinylene) films ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Solid-state 2H quadrupole echo nuclear magnetic resonance (NMR) spectra and measurements of 2H spin lattice relaxation times have been obtained for films of poly(p-phenylene vinylene) deuterated in phenylene ring positions (PPV-d4). NMR line shapes show that all the phenylene rings of PPV undergo 180° rotational jumps about the 1,4 ring axis (“ring flips”) at 225°C. The temperature dependence of the 2H line shapes show that the jump motion is thermally activated, with a median activation energy, Ea = 15 kcal/mol, and a distribution of activation energies of less than ±2 kcal/mol. The jump rate was also determined from the magnitude of the anisotropic T2 relaxation associated with 2H line shapes and from the curvature of inversion recovery intensity data. The experimental activation energy for jumps is comparable to the intramolecular potential barrier for rotation about phenylene vinylene bonds. 2H NMR provides a method for determining the phenylene-vinylene rotational barrier in pristine PPV, and may potentially be used to study conjugation in conducting films.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1992.090300102
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